My own experience, which I think is fairly generalizable, is that within the course of a single conversation hardly anybody ever changes their mind — including me.

He says he changes his opinion over time, though. What works for me is new information. Even if I'm not persuaded originally, new info might convince me - but maybe not so much because it's new but because it's a crutch, an excuse that lets me shed my stupid original opinion. Anyway, good for Kevin for reacting to Libya.